Q.

The coefficient of x301 in (1+x)500+x(1+x)499+x2(1+x)498+...+ x500 is               [2023]

1 C301500  
2 C200501  
3 C300500  
4 C302501  

Ans.

(2)

The coefficient of x301 in

(1+x)500+x(1+x)499+x2(1+x)498++x500

=C301500+C300499+C299498++C0199

=C199500+C199499+C199498++C199199=C200501